Messages in this thread | | | From | "Dilger, Andreas" <> | Subject | Re: [PATCH 03/10] staging: lustre: lu_object: discard extra lru count. | Date | Tue, 1 May 2018 04:19:54 +0000 |
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On Apr 30, 2018, at 21:52, NeilBrown <neilb@suse.com> wrote: > > lu_object maintains 2 lru counts. > One is a per-bucket lsb_lru_len. > The other is the per-cpu ls_lru_len_counter. > > The only times the per-bucket counters are use are: > - a debug message when an object is added > - in lu_site_stats_get when all the counters are combined. > > The debug message is not essential, and the per-cpu counter > can be used to get the combined total. > > So discard the per-bucket lsb_lru_len. > > Signed-off-by: NeilBrown <neilb@suse.com>
Looks reasonable, though it would also be possible to fix the percpu functions rather than adding a workaround in this code.
Reviewed-by: Andreas Dilger <andreas.dilger@dilger.ca>
> --- > drivers/staging/lustre/lustre/obdclass/lu_object.c | 24 ++++++++------------ > 1 file changed, 9 insertions(+), 15 deletions(-) > > diff --git a/drivers/staging/lustre/lustre/obdclass/lu_object.c b/drivers/staging/lustre/lustre/obdclass/lu_object.c > index 2a8a25d6edb5..2bf089817157 100644 > --- a/drivers/staging/lustre/lustre/obdclass/lu_object.c > +++ b/drivers/staging/lustre/lustre/obdclass/lu_object.c > @@ -57,10 +57,6 @@ > #include <linux/list.h> > > struct lu_site_bkt_data { > - /** > - * number of object in this bucket on the lsb_lru list. > - */ > - long lsb_lru_len; > /** > * LRU list, updated on each access to object. Protected by > * bucket lock of lu_site::ls_obj_hash. > @@ -187,10 +183,9 @@ void lu_object_put(const struct lu_env *env, struct lu_object *o) > if (!lu_object_is_dying(top)) { > LASSERT(list_empty(&top->loh_lru)); > list_add_tail(&top->loh_lru, &bkt->lsb_lru); > - bkt->lsb_lru_len++; > percpu_counter_inc(&site->ls_lru_len_counter); > - CDEBUG(D_INODE, "Add %p to site lru. hash: %p, bkt: %p, lru_len: %ld\n", > - o, site->ls_obj_hash, bkt, bkt->lsb_lru_len); > + CDEBUG(D_INODE, "Add %p to site lru. hash: %p, bkt: %p\n", > + o, site->ls_obj_hash, bkt); > cfs_hash_bd_unlock(site->ls_obj_hash, &bd, 1); > return; > } > @@ -238,7 +233,6 @@ void lu_object_unhash(const struct lu_env *env, struct lu_object *o) > > list_del_init(&top->loh_lru); > bkt = cfs_hash_bd_extra_get(obj_hash, &bd); > - bkt->lsb_lru_len--; > percpu_counter_dec(&site->ls_lru_len_counter); > } > cfs_hash_bd_del_locked(obj_hash, &bd, &top->loh_hash); > @@ -422,7 +416,6 @@ int lu_site_purge_objects(const struct lu_env *env, struct lu_site *s, > cfs_hash_bd_del_locked(s->ls_obj_hash, > &bd2, &h->loh_hash); > list_move(&h->loh_lru, &dispose); > - bkt->lsb_lru_len--; > percpu_counter_dec(&s->ls_lru_len_counter); > if (did_sth == 0) > did_sth = 1; > @@ -621,7 +614,6 @@ static struct lu_object *htable_lookup(struct lu_site *s, > lprocfs_counter_incr(s->ls_stats, LU_SS_CACHE_HIT); > if (!list_empty(&h->loh_lru)) { > list_del_init(&h->loh_lru); > - bkt->lsb_lru_len--; > percpu_counter_dec(&s->ls_lru_len_counter); > } > return lu_object_top(h); > @@ -1834,19 +1826,21 @@ struct lu_site_stats { > unsigned int lss_busy; > }; > > -static void lu_site_stats_get(struct cfs_hash *hs, > +static void lu_site_stats_get(const struct lu_site *s, > struct lu_site_stats *stats, int populated) > { > + struct cfs_hash *hs = s->ls_obj_hash; > struct cfs_hash_bd bd; > unsigned int i; > + /* percpu_counter_read_positive() won't accept a const pointer */ > + struct lu_site *s2 = (struct lu_site *)s;
It would seem worthwhile to change the percpu_counter_read_positive() and percpu_counter_read() arguments to be "const struct percpu_counter *fbc", rather than doing this cast here. I can't see any reason that would be bad, since both implementations just access fbc->count, and do not modify anything.
> + stats->lss_busy += cfs_hash_size_get(hs) - > + percpu_counter_read_positive(&s2->ls_lru_len_counter); > cfs_hash_for_each_bucket(hs, &bd, i) { > - struct lu_site_bkt_data *bkt = cfs_hash_bd_extra_get(hs, &bd); > struct hlist_head *hhead; > > cfs_hash_bd_lock(hs, &bd, 1); > - stats->lss_busy += > - cfs_hash_bd_count_get(&bd) - bkt->lsb_lru_len; > stats->lss_total += cfs_hash_bd_count_get(&bd); > stats->lss_max_search = max((int)stats->lss_max_search, > cfs_hash_bd_depmax_get(&bd)); > @@ -2039,7 +2033,7 @@ int lu_site_stats_print(const struct lu_site *s, struct seq_file *m) > struct lu_site_stats stats; > > memset(&stats, 0, sizeof(stats)); > - lu_site_stats_get(s->ls_obj_hash, &stats, 1); > + lu_site_stats_get(s, &stats, 1); > > seq_printf(m, "%d/%d %d/%ld %d %d %d %d %d %d %d\n", > stats.lss_busy, > >
Cheers, Andreas -- Andreas Dilger Lustre Principal Architect Intel Corporation
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